Assembly for desorbing sampling tubes; adapter and sampling tubes for such an assembly; and kit of parts for forming such as assembly

ABSTRACT

An assembly for desorbing sampling tubes comprises a gas chromatograph known per se provided with an injector. The sampling tubes are provided with an inflow opening and an outflow opening. The assembly comprises an adapter which is placed in the injector and which is provided with a chamber which is bounded by a heat conducting housing. The adapter is arranged for placing a sampling tube in the chamber thereof, while in a condition of a sampling tube wherein it is placed in the adapter, the inflow opening thereof is in fluid communication with a first carrier gas supply duct, while the outflow opening of the sampling tube is in fluid communication via the injector with a gas chromatography column disposed in the gas chromatograph.

This application claims the priority of Dutch application no. NL1012127, filed May 21, 1999, which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to an assembly for desorbing samplingtubes.

2. Background of the Invention.

It is well known to store samples of gases, liquids or like fluids inso-called sampling tubes. To that end, see, for instance, EP-A-0 816823, the disclosure of which is to be considered inserted herein. Alsosolid substance in the form of granules or the like is stored insampling tubes. Often, but not always, such sampling tubes are filledwith absorption material in which the gas or the liquid, at least thesubstances present therein, are absorbed. Such sampling tubes are used,for instance, in surroundings where the danger exists that theatmosphere becomes contaminated, as in, for instance, laboratories,chemical factories, submarines and the like. Thus there are samplingtubes where the air to be measured is actively pumped through thesampling tube and where the sampling tube is therefore provided with aninflow opening and an outflow opening. When a sample of a gas to besampled is being taken, the gas is pumped into the inflow opening, andthe gas leaves the sampling tube via the outflow opening while leavingthe substances contained in the gas behind in the absorption material.This procedure of sampling is designated as active sampling. Also known,from practice, is so-called passive sampling. In that case the samplingtubes have only one inflow opening during sampling. The air or the gasto be sampled diffuses via that opening into the absorption materialwhile leaving the substances contained in the gas behind in theabsorption material.

After some time has passed after sampling, the sampling tube isdesorbed. To that end, heretofore, use has been made of special deviceswhich are particularly costly. Desorption of the sampling tube occurs byheating the sampling tube, so that the substances present in theabsorption material or in the solid substance contained in the samplingtube evaporate and are liberated. By blowing a carrier gas through thesampling tube during heating, the liberated substances are entrained bythe carrier gas and can, for instance, be temporarily collected in acold trap and subsequently be passed from the cola trap to a gaschromatograph in which the gases released can be analyzed. The knowndesorption devices are therefore provided with carrier gas supply means,heating means, a cold trap, control means for controlling the heatingmeans and the like. This has as a result that the known desorptiondevices have a considerable cost price, which are of the order of a fewtens of thousands of guilders.

SUMMARY OF THE INVENTION

The invention envisages an entirely new type of assembly by means ofwhich sampling tubes can be desorbed, and which has a much lower costprice. Essentially, the invention is based on the insight that the gaschromatograph, which is necessary anyhow, essentially has all the meansthat are also used in a known desorption device. By means of theassembly, these means already present in the gas chromatograph are madeavailable for desorbing sampling tubes.

To that end, the invention provides an assembly for desorbing samplingtubes, the assembly comprising a gas chromatograph known per se providedwith an injector, the sampling tubes having an inflow opening and anoutflow opening, the assembly comprising an adapter which is placed inthe injector and which is provided with a chamber which is bounded by aheat conducting housing, the adapter being arranged for placing asampling tube in the chamber thereof, while in a condition where asampling tube is placed in the Adapter, the inflow opening of thesampling tube is in fluid communication with a first carrier gas supplyduct, while the outflow opening of the sampling tube is in fluidcommunication via the injector with a gas chromatography columncontained in the gas chromatograph.

Due to the heat conducting housing of the adapter which bounds a chamberin which a sampling tube can be placed, it is possible by means of theheating means situated in the known injector of the known gaschromatograph, to heat a sampling tube placed in the chamber mentioned.Because moreover the inflow opening of the sampling tube is in fluidcommunication with a first carrier gas supply duct, and the outflowopening of the sampling tube is in fluid communication, via theinjector, with a gas chromatography column contained in the gaschromatograph, substances located in the sampling tube that areliberated under the influence of the heating of the tube, can flow alongwith the carrier gas and be analyzed in the gas chromatography column.Since the known gas chromatograph has an extensive control by means ofwhich the heating means of the injector can be accurately set, thetemperature of the sampling tube contained in the chamber of the adaptercan be accurately controlled, so that any particular temperature courseof the sampling tube can be realized very accurately Thus, for instance,first the light fractions contained in the sampling tube can be releasedby heating the sampling tube to, for instance, 50° C. for some time,whereafter subsequently heavier fractions can be liberated by heatingthe sampling tube to, for instance, 150°-250° C.

According to a further elaboration, it is particularly favorable whenthe adapter is provided with a heat conducting tube which is connectedwith the heat conducting housing, such that the tube and the housing arein heat exchange with each other, while the tube of the adapter, in thefitted condition of the adapter, reaches into the injector chamber.Because the tube reaches into the injector chamber, the heat transferfrom the heating means of the injector will occur much more efficientlyin that the tube of the adapter is directly surrounded by the heatingmeans of the injector.

According to a further elaboration of the invention, it is particularlyfavorable when the sampling tubes have the shape of a vial known per se.When, according to a further elaboration of the invention, the assemblyfurther comprises an autosampler known per se, which autosamplercomprises a setup rack in which a number of vial-shaped sampling tubescan be set up, while the manipulator of the autosampler is arranged forpicking up a sampling tube from the setup rack and placing such samplingtube in the adapter.

With such a device, without intervention of a laboratory worker, a largenumber of sampling tubes can be desorbed. Normally, the autosamplerknown per se is used to spout a liquid sample contained in a vial fromthis vial into the injector. The manipulator of the autosampler movesthe vial in question from the setup rack into what is designated inpractice by the term turret, from where an automatically operable spoutsucks up the sample from the vial and then injects it into the injectorof the gas chromatograph. As a result of the fact that the samplingtubes have the same shape as a vial known per se, the autosampler inmost cases already present can be used for converting the gaschromatograph to a sampling tube desorbing device.

The invention also relates to an adapter evidently intended for use inan assembly according to the invention. Further, the invention relatesto a sampling tube evidently intended for use in an assembly accordingto the invention.

Furthermore, the invention relates to a kit of parts comprising at leastone adapter according to the invention, as well as a support formounting an autosampler known per se on a gas chromatograph known perse, the support being designed such that the autosampler can place thesampling tubes in the adapter, which is placed in an injector of the gaschromatograph, without requiring adjustment of the control of theautosampler. It is then preferred when the kit also comprises variouscarrier gas ducts, at least one T-piece and a valve assembly.

DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated with reference to the drawing,wherein

FIG. 1 shows a perspective view of a gas chromatograph known per se ofthe firm Hewlett Packard®, with a part of the top of the housing of thegas chromatograph broken away, and with the injector shown partly inexploded view;

FIG. 2 shows a perspective view of an autosampler known per se of thefirm Hewlett Packard®, which is mounted on the upper left corner of thegas chromatograph shown in FIG. 1;

FIG. 3 shows a side elevation of a vial known per se;

FIG. 4 shows a perspective view of a setup rack of an autosampler knownper se with an associated manipulator;

FIG. 5 shows a cross section of a part of the injector with an adapterplaced therein and a sampling tube placed in the adapter;

FIG. 6 shows a cross sectional view of the relevant parts of the adapterrepresented in FIG. 5;

FIG. 7 shows a cross sectional view of a sampling tube that isrepresented in FIG. 5;

FIG. 8 shows in more detail how the adapter is mounted in the injectorand the manner in which the inflow opening and the outflow opening ofthe sampling tube have been set into fluid communication with a carriergas supply duct and a capillary, respectively;

FIG. 9 shows a schematic view of an assembly according to the inventionduring the desorption of a sampling tube;

FIG. 10 shows a similar schematic representation to that represented inFIG. 9 during the analysis phase of a desorbed sampling tube;

FIG. 11 shows a sampling tube of alternative design with a carrier gassupply duct which is included in a swiveling arm; and

FIG. 12 shows a similar view to that represented in FIG. 10, where theswivel arm has taken a second position.

DETAILED DESCRIPTION OF THE INVENTION

The gas chromatograph represented in FIG. 1 is marketed by HewlettPackard® and comprises a housing 2 in which an oven chamber is includedwhich is closed off with an oven door 3. The housing 2 further containsa control which is operable by means of the control panel 4. In the ovenchamber, in the present exemplary embodiment two, gas chromatographycolumns may be disposed, which are generally designed as capillary tubesprovided with an internal coating. Such gas chromatography columns 42are connected by an inlet end to a so-called injector 5 and by an outletend to a so-called detector 6. In the exemplary embodiment shown, twodetectors 6 are represented and two openings 7 in the top of the housing2 for the purpose of injectors 5. The injectors 5 are provided withheating means in the form of a spiral filament which extends around aninjector chamber into which normally the liquid to be analyzed isinjected. Often injection occurs by means of a so-called autosamplerwhich is mounted on the upper left corner of the gas chromatograph 1.Such an autosampler 8 is represented in perspective in FIG. 2 andcomprises inter alia a setup rack 9 provided with a large number ofopenings 10 for receiving vials 11. A vial 11 is a vessel in which aliquid sample can be stored. By way of example, an exemplary embodimentof a vial 11 is represented in FIG. 3, with the specified dimensionsbeing indicated in millimeters. The autosampler 8 further comprises anarm 12 which carries a gripper 13. The gripper 13 is provided with agripper jaw 14 by means of which, in the use according to the prior art,vial 11 can be picked up from the tray 9. Optionally, the vial 11 canthen be moved past a reader 15, so that a code carried by the vial canbe read. The manipulator 12-14 of the autosampler 8, which manipulatorcomprises the arm 12, the gripper 13 and the gripper jaw 14, places avial 11 taken from the setup rack 9, in the known use, in a so-calledturret. This turret 16 is situated under a tower 17. Disposed in thistower 17 is an automatically energized injection needle by means ofwhich liquid can be sucked up from a vial 11 which is disposed in theturret 16 and subsequently can be injected into the injector 5 of thegas chromatograph 1. The turret 16 mostly contains other liquidreservoirs with cleaning liquid for cleaning the injection needle afterit has sucked up a sample from a vial 11 and delivered it to theinjector 5. All devices discussed so far with reference to the drawingsbelong to the state of the art and are marketed inter alia by HewlettPackard®.

FIG. 5 shows the housing 18, bounding the injector chamber, of theinjector known per se. In this injector chamber, an adapter 19 is placedin which a sampling tube 20 is received. The adapter 19 is connectedwith the housing 18 of the injector chamber by means of a retaining nut21, which housing 18 forms part of a standard injector. It is clearlyvisible that the housing 18 is provided with a so-called split-offchannel 22 which is in fluid communication with the interior of theinjector chamber. Further, a needle 23 is clearly shown, in which acapillary duct 24 extends as far as an outflow opening 25 of thesampling tube 20. An inflow opening 26 of the sampling tube 20 is influid communication with the injector chamber which is bounded by thehousing 18.

For the purpose of a gas-tight closure adjacent the top of the injectorchamber bounded by the injector housing 18, a sealing ring 27 isprovided, which is clamped between the adapter 19 and the injectorchamber housing 18.

FIG. 6, for the sake of clarity shows the adapter 19, the fastening nut21 and the sealing ring 27 in disassembled condition. The adapter 19 ofthe present exemplary embodiment comprises a chamber K which is boundedby a heat conducting housing 29. Further, the adapter 19 comprises aheat conducting tube 30 which is connected with the housing 29 such thatthey are in heat exchange with each other. In the present exemplaryembodiment, the tube 30 and the housing 29 are constructed as a singleintegral part. Further, in the present exemplary embodiment, in the wallof the tube 30 a bore 28 is provided which, in the condition of theadapter 19 when fitted in the injector 18, is in fluid communicationwith the split-off channel 22 of the injector housing 18, as is clearlyrepresented in FIG, 5. Although the heat conduction to the chamber K asa result of the presence of the heat conducting tube 30 is very good, itis also possible, according to an alternative elaboration of theinvention, that the adapter is not provided with a heat conducting tubewhich reaches into the injection chamber bounded by the injector housing18. To bring the temperature in the chamber K of the adapter to thedesired value, it is then necessary that the heating means of theinjector 5 are set at a higher temperature. It is self-explanatory thata design with heat conducting tube 30 is preferred. Further, the housing29 of the adapter comprises a collar 31 which is engaged by thefastening nut 21 and against which the sealing ring 27 abuts when theadapter is mounted on the injector housing 18.

FIG. 7 shows an exemplary embodiment of a sampling tube 20 which can beused in the adapter 19 which is represented in FIGS. 5 and 6. To enablethe sampling tubes 20 to be automatically placed in the adapter 19 bymeans of the autosampler 8 from FIG. 2, the sampling tube 20 representedin FIG. 7 has substantially the same dimensions as the vial 1 which isrepresented in FIG. 3. Consequently, the sampling tubes 20 can beaccommodated in the openings 10 of the setup rack 9 and be effectivelyengaged by the gripper 13 of the manipulator 12, 13, 14 of theautosampler 8 known per se. The sampling tube 20 which is represented inFIG. 7 is provided with an inflow opening 26 and an outflow opening 25which are provided at the same end 20 a of the sampling tube 20. Thesampling space B of the sampling tube 20 will generally contain anabsorption material, such as, for instance, Tenax® (trademark of thefirm Akzo; polyphenylene oxides). However, other absorption materialscan also be selected, for instance activated carbon such as, forinstance, carbograph™, carbosieve™ and carbotrap™ and other absorbingpowders or granular materials such as silica gel, deactivated aluminumand the like. Further, it is possible that the chamber B of the samplingtube 20 is filled with a solid substance in granular form on which themeasurement itself is to be performed, such as for instance a groundplastic or the like. Connected to the inflow opening 26 of the samplingtube 20 is a duct 32 having a first end 32 a. The duct 32 extendsthrough the inner chamber B of the sampling tube 20 and terminatesthrough a second end 32 b adjacent a second end 20 b of the samplingtube, located opposite the first end 20 a of the sampling tube. Thefirst end 20 a of the sampling tube 20 is provided with a first sealingring 33 which is adapted for creating a fluid-tight seal between thetapering underside K1 of the chamber K of the adapter 19. Further, theend 20 a of the sampling tube 20 is provided with a second sealing ring34 which connects in a fluid-tight manner to a capillary 35 which isinserted into the outflow opening 25 of the sampling tube 20. FIG. 8shows clearly the manner in which the sealing rings 33 and 34 cooperaterespectively with the tapered underside K1 of the chamber K and acapillary column 35 reaching into the inflow opening. Further, it isclear from FIG. 8 in what way the fastening nut 21 secures the adapter19 to the injector housing 18, with the sealing ring 27 forming a sealAlso visible is the bore 28 in the wall of the tube 30 of the adapter 19and the manner in which it has been set in fluid communication with thesplit-off channel 22 of the injector. When the adapter 19 is mounted inthe injector housing 18, a needle 36 reaches at least into the undersideK1 of the chamber K of the adapter. This hollow needle 36 surrounds thecapillary 35 which reaches slightly further into the chamber K of theadapter. When placing a sampling tube 20 in the adapter 19, thecapillary 35 is automatically pushed beyond the sealing ring 34, so thata fluid communication between the capillary 35 and the inner chamber Bof the sampling tube is effected. The inflow opening 26 of the samplingtube 20 is in fluid communication with the inner space S of the tube 30,which is fluid-tightly closed at the lower end, where it allows only theneedle 36 and the capillary 35 to pass. In that way, therefore, a fluidcommunication is created between the inflow opening 26 and the split-offchannel 22 of the injector 5. In the present exemplary embodiment, thereis connected to the split-off channel 22 a carrier gas supply duct 41with which carrier gas is supplied to the inner space S of the heatconducting tube 30. From this inner space S, the carrier gas flows tothe inflow opening 26 of the sampling tube 20 and via the duct 32 to asecond end 20 b of the sampling tube. There the carrier gas flows intothe inner chamber B of the sampling tube and there will have topenetrate through the absorption material to reach the outflow opening25. The heating means of the injector chamber 5 are meanwhile heated up,so that the heat conducting tube 30 of the adapter 19 is heated. Theheat in the heat conducting tube 30 is passed on to the heat conductinghousing 29 bounding the chamber K of the adapter 19. Consequently, thesampling tube 20 will rise in temperature, so that the substancescontained in the absorption material are liberated by evaporation andentrained with the carrier gas. To prevent the absorption material fromending up in the capillary 35, the needle 36 or the inner space S of theheat conducting tube 30, the absorption tube is provided with a screen37 adjacent the outflow opening.

The sampling tube 20 represented in FIG. 7 is suitable for activesampling. To that end, a pump is connected to the first end 20 a of thesampling tube 20, which pumps the gas to be sampled via the inflowopening 26 into the sampling tube 20 or sucks the gas to be sampled fromthe outflow opening 25 through the sampling tube 20 On the other hand,it is possible to use the sampling tube 20 for passive desorption. Thenthe first end 20 a is closed off by means of a cap and the closing plate38 is replaced with a screen. Via the opening 39 in the cover 40 of thesampling tube 20, the gas to be sampled can, by diffusion, diffuse intothe interior B of the sampling tube 20, When the sampling tubes 20 aresubsequently to be desorbed, the screen adjacent the second end 20 b isreplaced by a closing plate 38 and the cap which closes off the firstend 20 a of the sampling tube 20 is removed.

It is noted that the sampling tube 20 is preferably made of inertmaterial, such as, for instance, glass, metal, ceramics, Teflon® (PTFE)or Vespel® (both trademarks of Dupont). To manufacture the sampling tube20 in an economically advantageous manner, it can be manufactured fromteflon by means of an injection molding process. Optionally, in thesampling tube in question, a transponder may be included in which anidentification code and/or data about the sampling are stored. While thesampling tube is being placed from the setup rack 9 in the adapter 19,the transponder can be momentarily read in the reader 15 (see FIG. 2),so that the gas chromatograph 1 can run the correct program fordesorbing the tube 20 in question.

FIGS. 9 and 10 show a schematic view of the assembly. FIG. 9 shows thedesorption phase and FIG. 10 the analysis phase. FIGS. 9 and 10schematically show the gas chromatograph 1 with the injector 5 on theleft-hand side and the detector 6 on the right-hand side. The injector 5and the detector 6 are in fluid communication with each other, interalia via the gas chromatography column 42. In the injector 5, an adapter19 as described hereinbefore is placed. In the chamber K of the adapter19, a sampling tube 20 is placed. The inlet 26 of the sampling tube 20in fluid communication with a first carrier gas duct 41 which isconnected to the split-off channel 22 of the injector 5. The split-offchannel 22 is also clearly represented in FIG. 5 and forms part of theinjector housing 18. The other end of the first carrier gas supply duct41 is connected with a first outlet 43 b of a valve assembly 43, whichin the present exemplary embodiment is designed as a three-way valve.The inlet 43 a of the three-way valve 43 is connected with a carrier gasmain supply duct 45. A second outlet 43 c of the three-way valve 43 isconnected to a second carrier gas supply duct 44. The three-way valve 43sets the carrier gas main supply duct 45 in fluid communication witheither the first carrier gas supply duct 41 or the second carrier gassupply duct 44. It is evident that the valve assembly 43 can also bedesigned as two single valves. The assembly further comprises a coldtrap 46 which is arranged in the oven chamber O of the gas chromatograph1. Such a cold trap 46 is formed by a capillary duct which is surroundedby a jacket, which jacket is cooled by means of, for instance, liquidnitrogen. As a result of the very low temperature prevailing in the coldtrap 46, all substances desorbed from the sampling tube 20 will condensetherein and be retained. As soon as the cooling of the cold trap 46 isswitched off, and the capillary is heated up by means of the oven of thegas chromatograph 1, the substances condensed in the cold trap 46 willevaporate again and be liberated for analysis. The assembly furthercomprises a first connecting duct 47 which sets the capillary discharge35 of the injector 5 in fluid communication with an inlet 46 a of thecold trap 46. A second connecting duct 48 connects an outlet 46 b of thecold trap 46 with the gas chromatography column 42. It is noted that thedischarge 35, the first connecting duct 47, the cold trap 46 and thesecond connecting duct 48 are preferably designed as a capillary duct inwhich upstream and downstream of the cold trap, respectively, a firstT-junction 49 and a second T-junction 50 are provided. Connected to thefirst T-junction 49 is an outlet of the second carrier gas supply duct44, while a discharge duct 51 is connected to the second T-junction 50.The T-junctions 49, 50 can be designed in a variety of ways and areknown per se

During the desorption phase, which is represented in FIG. 9, thethree-way valve 43 is set in a position such that the carrier gas mainsupply duct 45 is in fluid communication with the first carrier gassupply duct 41. The carrier gas flows via the split-off channel 22 ofthe injector 5 into the interior of the tube 30 of the adapter and fromthere via the inflow opening 26 of the sampling tube 20 and the duct 32in the sampling tube 20 into the interior B of the sampling tube. Thecarrier gas proceeds to flow through the absorption material in thesampling tube 20 to the outflow opening 25 which is connected to thecapillary 35 which forms the outlet or discharge of the injector Thiscapillary 35 leads to the first T-junction 49 and is in fluidcommunication with the first connecting duct 47 which leads to the coldtrap 46. Because the adapter 19 is heated by the heating means of theinjector 7, substances contained in the absorption material will beliberated and be entrained with the carrier gas passed through thesampling tube 20. This carrier gas flows to the cold trap 46 in whichthe substances condense from the carrier gas. As soon as the control ofthe gas chromatograph has determined that the desorption of the samplingtube 20 has taken place sufficiently long, the three-way valve 3 can beset in the second position, which is shown in FIG. 10. In this secondposition, the carrier gas main supply duct 45 is in fluid communicationwith the second carrier gas supply duct 44. The heating means of theinjector 5 can be switched off since the desorption process has beencompleted and presently the analyzing process can take place. Thecooling of the cold trap 46 can be switched off, so that the temperaturein the cold trap 46 will rise rapidly to the temperature prevailing inthe oven chamber O of the gas chromatograph 1. Preferably, the heatcapacity of the cold trap is to be held low, for instance by designingthe cold trap 46 as a capillary which is surrounded by a needle, throughwhich needle liquid nitrogen can be passed. As soon as the temperaturein the cold trap 46 rises, the substances condensed therein will startto evaporate and be entrained by the carrier gas which is supplied tothe cold trap 46 via the second carrier gas supply duct 44 and the firstT-junction 49 via the first connecting duct 47. From the cold trap 46the carrier gas flows via the second connecting duct 48 to the secondT-junction 50 to which an inlet of the gas chromatography column 42 isconnected. At least a part of the carrier gas therefore flows throughthe gas chromatography column 42, where a separation of the substancesoccurs, so that they end up successively in the detector 6, on the basisof which it can be determined what substances were present in theabsorption material of the sampling tube 20. By stepwise raising thetemperature in the oven chamber O, first the light fractions can beliberated from the cold trap 46 and then the heavier fractions.

Hereinabove, a sampling tube 20 has been discussed in which the inflowopening 26 and the outflow opening 25 are situated at a first end 20 aof the sampling tube 20. This has as an advantage that, when placing thesampling tube 20, in a very simple manner both the inflow opening 26 andthe outflow opening 25 can be set in fluid communication with a carriergas supply duct 41 and the gas chromatography column 42, respectively.It is also possible, however, according to an alternative furtherelaboration of the invention, that the sampling tube 120 is providedwith an inflow opening 126 on a second end 120 b and an outflow opening125 on a first end 120 a of the sampling tube 120. It is then necessary,however, that the assembly is provided with a movable first carrier gassupply duct 141 of which an outflow opening 141 a is adapted to beconnectable to the inflow opening 126 of the sampling tube 120. In awall of the housing 29 of the chamber K of the adapter 19 a discharge 35is provided which, in the condition of the sampling tube 20 when placedin the chamber K, connects to the outflow opening 125 of the samplingtube 120. In the exemplary embodiment represented in FIGS. 11 and 12,the movable carrier gas supply duct 141 is included in a swiveling arm53. The swiveling arm 53 is provided with a carrying cam 154 which, asthe sampling tube 120 is fitted, is engaged by the lower edge of thecover 140 of the sampling tube 120. With this engagement, the swivelingarm 53 gradually swivels along with the movement of the sampling tube120, while simultaneously the outflow opening 141 a of the first carriergas supply duct 141 is pushed into the inflow opening 126 of thesampling tube 120.

FIG. 11 shows a position of the sampling tube 20 and the swiveling arm53 at the beginning of the engagement and FIG. 12 shows the swivelingarm 53 and the sampling tube 120 in a condition in which the samplingtube 120 is disposed in the chamber K of the adapter 19. Clearly visibleis that the outflow opening 141 a of the first carrier gas supply duct141 has been set to connect to the inflow opening 126 of the samplingtube 120. Further, it is clearly visible that the discharge 35 has beenset into fluid communication with the outflow opening 125 of thesampling tube 120.

It will be clear that the invention is not limited to the exemplaryembodiments described but that various modifications within the scope ofthe invention are possible. Essential is that as a result of thepresence of the adapter which has been placed in the injector, a gaschromatograph known per se can be used as desorption device for samplingtubes.

The fact that from the outflow opening 25 of the desorption tube thecapillary 35 and the first connecting duct 47 as far as the cold trap 46are wholly heated—since they are disposed in the oven chamber O of thegas chromatograph 1—precludes desorbed substances precipitating on theseduct parts before they reach the cold trap 46. This provides theadvantage that no substances that were present in the sampling tube arelost during the desorption process. The accuracy of the measurementtaking place in the gas chromatograph is thereby influenced in apositive way. In the known desorption devices which are arrangedseparately from the gas chromatograph, this danger is definitelypresent. Not only is the known desorption device much more costly thanis the proposal according to the invention, but also the accuracy of theknown device is lesser than that of the proposal according to theinvention.

What is claimed is:
 1. An assembly for desorbing sampling tubes (20),the assembly comprising a gas chromatograph (1) known per se providedwith an injector (5), the sampling tubes (20) being provided with aninflow opening (26) and an outflow opening (25), the assembly comprisingan adapter (19) which is placed in the injector (5) and which isprovided with a chamber (K) which is bounded by a heat conductinghousing (29), placed in thermal communicating contact with a gaschromatograph oven chamber (O), the adapter (19) being arranged forplacing a sampling tube (20) in the chamber (K) thereof, while in amounted condition of a sampling tube (20) wherein it is placed in theadapter (19), the inflow opening (26) thereof is in fluid communicationwith a first carrier gas supply duct (41), while the outflow opening(25) of the sampling tube (20) is in fluid communication via theinjector (5) with a gas chromatography column (42) disposed in the gaschromatograph (1), further comprising a valve assembly (43), a secondcarrier gas supply duct (44), carrier gas main supply duct (45); whereinan at least one inlet of the valve assembly (43 a) is connected to thecarrier gas main supply duct (45); wherein a first outlet (36) of thevalve assembly (43) is connected to the first carrier gas supply duct(41); wherein a second outlet (43 c) of the valve assembly (43) isconnected to the second carrier gas supply duct (44); wherein the valveassembly (43) sets the carrier gas main supply duct (45) in fluidcommunication with either the first carrier gas supply duct (41) or thesecond carrier gas supply duct (44); wherein the assembly furthercomprises a cold trap (46), which is arranged in the oven chamber (0) ofthe gas chromatograph (1), as well as a first connecting duct (47) whichsets the outlet of the injector (7) in fluid communication with an inlet(46 a) of the cold trap (46); wherein a second connecting duct (48) setsan outlet (46 b) of the cold trap (46) in fluid communication with thegas chromatography column (42); wherein a downstream end of the gaschromatography column (42) is in communication with a detector (6);wherein upstream of the cold trap (46) and downstream of the injectoroutlet a first T-junction (49) is provided in the first connecting duct(47), to which an outlet of the second carrier gas supply duct (44) isconnected; wherein a second T-junction (50) is provided in the secondconnecting duct (48), to which a discharge duct (51) is connected.
 2. Anassembly for describing sampling tubes (20), the assembly comprising agas chromatograph (1) known per se provided with an injector (5), thesampling tubes (20) being provided with an inflow opening (26) and anoutflow opening (25), the assmebly comprising an adapter (19) which isplaced in the injector (5) and which is provided with a chamber (K)which is bounded by a heat conducting housing (29), placed in thermalcommunicating contact with a gas chromatograph oven chamber (O), theadapter (19) being arranged for placing a sampling tube (20) in thechamber (K) thereof, while in a mounted condition of a sampling tube(20) wherein it is placed in the adapter (19), the inflow opening (26)thereof is in fluid communication with a first carrier gas supply duct(41), while the outflow opening (25) of the sampling tube (20) is influid communication via the injector (5) with a gas chromatographycolumn (42) disposed in the gas chromograph (1), characterized in thatthe adapter (19) is provided with a heat conducting tube (30) which isconnected with the heat conducting housing (29), such that the tube (30)and the housing (29) are in heat exchange with each other, while thetube (30) of the adapter (19), in the mounted condition of the adapter(19), reaches into the injector chamber.
 3. An assembly according toclaim 2, characterized in that the injector (5) comprises a split-offchannel (22), the first carrier gas supply duct (41) being connected tothe split-off channel (22).
 4. An assembly according to claim 1,characterized in that the sampling tubes (20) used therein are providedwith an inflow opening (26) and an outflow opening (25) which aresituated on the same end (20 a) of the sampling tube (20), while in awall of the housing (29) of the chamber (K) of the adapter (19( both asupply (52) and a discharge (35) are provided which, in a condition ofthe sampling tube (20) when placed in the chamber (K), connect to,respectively, the inflow opening (26) and the outflow opening (25) ofthe sampling tube (20).
 5. An assembly according to claim 1,characterized in that the sampling tubes (120) used therein are providedwith an inflow opening (126) on a second (120 b) and an outflow opening(125) on a first end (120 a) of the sampling tube (120), the assemblycomprising a displaceable first carrier gas supply duct (141) of whichan outflow opening (141 a) is adapted to be connectable with the inflowopening of the sampling tube (120), while in a wall of the housing (29)of the chamber (K) of the adapter (19) a discharge (35) is providedwhich, in a condition of a sampling tube (120) when placed in thechamber, connects to the outflow opening (125) of the sampling tube(120).
 6. An assembly according to claim 5, characterized in that thedisplaceable first carrier gas supply duct (141) extends in a swivelingarm (53).
 7. An assembly according to claim 5, characterized in that (a)sampling tube (20, 120) has the shape of a vial known per se, (b) theassembly further comprises an autosampler (8) known per se, whichautosampler (8) comprises a setup rack (10) in which a number ofsampling tubes (20, 120) can be set up, while a manipulator (12, 13, 14)of the autosampler (8) is adapted for picking up a sampling tube (20,120) from the setup rack (10) and placing such a sampling tube (20, 120)in the adapter (19) and (c) said autosampler (8) is mounted on a base(54) which is connected with a housing of the gas chromatograph (1). 8.An assembly according to claim 1, characterized in that (a) the samplingtube (20, 120) has the shape of a vial known per se, (b) the assemblyfurther comprises an autosampler (8) known per se, which autosampler (8)comprises a setup rack (10) in which a number of sampling tubes (20,120) can be set up, while a manipulator (12, 13, 14) of the autosampler(8) is adapted for picking up a sampling tube (20, 120) from the setuprack (10) and placing such a sampling tube (20, 120) in the adapter(19), and (c) the chromatograph (1) comprises two injectors (7), whilein each injector (5) an adapter (19) is arranged, the autosampler (8)being arranged for placing a sampling tube (20, 120) in both the one andthe other adapter (19).
 9. An adapter comprising an assembly accordingto claim 1, characterized in that (a) the adapter comprises a heatconducting housing (29) which bounds a chamber (K), the adapter (19)further comprising a heat conducting tube (30) which is connected withthe housing (20) such that they are in heat exchange with each other,and (b) the housing (20) and the tube (30) are constructed as a singlepart.
 10. An adapter according to claim 9 characterized in that in thewall of the tube (30) a bore (28) is provided which, in a mountedcondition of the adapter (19) in the injector (5) is in fluidcommunication with the split-off channel (22) of the injector (5).
 11. Asampling tube comprising an assembly according to claim 1, characterizedin that the sampling tube (20, 120) is filled with an adsorptionmaterial.
 12. A sampling tube according to claim 11, characterized inthat the sampling tube (20, 120) is filled with an adsorption material.13. A sampling tube according to claim 11, characterized in that thesampling tube (20, 120) has the form of a vial known per se.
 14. Asampling tube according to claim 11, characterized in that the samplingtube (20,120) is provided with a transponder.
 15. A sampling tubeaccording to claim 11, characterized by an inflow opening (26) and anoutflow opening (25) which are situated at a first end (20 a) of thesampling tube (20), while in the interior (B) of the sampling tube (20)a duct (32) extends which is connected by a first end (32 a) to theinflow opening (26) and which terminates by a second end (32 b) in theinterior (B) of the sampling tube (20) adjacent a second end (20 b) ofthe sampling tube(20), situated opposite the first end (20 a) of thesampling tube (20).
 16. A sampling tube according to claim 11,characterized in that the sampling tube (20) is manufactured from aninert material.
 17. A sampling tube according to claim 11, characterizedin that the sampling tube (20) is manufactured from an inert material,characterized in that it has been manufactured from TEFLON® by means ofan injection molding process.
 18. A kit of parts, comprising at leastone adapter (19) according to claim 9, as well as a support (54) formounting an autosampler (8) known per se on a gas chromatograph (1)known per se, the support (54) being so designed that the autosampler(8) is capable of placing the sampling tubes (20,120) in the adapter(19) which has been placed in an injector (5) of the gas chromatograph(1), without requiring adjustment of the control of the autosampler (8).19. A kit according to claim 18, characterized by various carrier gasducts (41, 44, 45), at least one T-piece (49, 50) for forming aT-junction as described in claim 3 and a valve assembly (43).
 20. Theassembly according to claim 2, further comprising a valve assembly (43),a second carrier gas supply duct (44), carrier gas main supply duct(45); wherein an at least one inlet of the valve assembly (43 a) isconnected to the carrier gas main supply duct (45); wherein a firstoutlet (36) of the valve assembly (43) is connected to the first carriergas supply duct (41); wherein a second outlet (43 c) of the valveassembly (43) is connected to the second carrier gas supply duct (44);wherein the valve assembly (43) sets the carrier gas main supply duct(45) in fluid communication with either the first carrier gas supplyduct (41) or the second carrier gas supply duct (44); wherein theassembly further comprises a cold trap (46), which is arranged in theoven chamber (0) of the gas chromatograph (1), as well a firstconnecting duct (47) which sets the outlet of the injector (7) in fluidcommunication with an inlet (46 a) of the cold trap (46); wherein asecond connecting duct (48) sets an outlet (46 b) of the cold trap (46)in fluid communication with the gas chromatography column (42); whereina downstream end of the gas chromatography column (42) is incommunication with a detector (6); wherein upstream of the cold trap(46) and downstream of the injector outlet a first T-junction (49) isprovided in the first connecting duct (47), to which an outlet of thesecond carrier gas supply duct (44) is connected; wherein a secondT-junction (50) is provided in the second connecting duct (48), to whicha discharge duct (51) is connected.
 21. The assembly according to claim2, characterized in that the sampling tubes (20) used therein areprovided with an inflow opening (26) and an outflow opening (25) whichare situated on the same end (20 a) of the sampling tube (20), while ina wall of the housing (29) of the chamber (K) of the adapter (19( both asupply (52) and a discharge (35) are provided which, in a condition ofthe sampling tube (20) when placed in the chamber (K), connect to,respectively, the inflow opening (26) and the outflow opening (25) ofthe sampling tube (20).
 22. The assembly according to claim 2,characterized in that the sampling tubes (120) used therein are providedwith an inflow opening (126) on a second (120 b) and an outflow opening(125) on a first end (120 a) of the sampling tube (120), the assemblycomprising a displaceable first carrier gas supply duct (141) of whichan outflow opening (141 a) is adapted to be connectable with the inflowopening of the sampling tube (120), while in a wall of the housing (29)of the chamber (K) of the adapter (19) a discharge (35) is providedwhich, in a condition of a sampling tube (120) when placed in thechamber, connects to the outflow opening (125) of the sampling tube(120).
 23. A nadapter comprising the assembly according to claim 2,characterized in that (a) the adapter comprises a heat conductinghousing (29) which bounds a chamber (K), the adapter (19) furthercomprising a heat conducting tube (30) which is connected with thehousing (20) such that they are in heat exchange with each other, and(b) the housing (20) and the tube (30) are constructed as a single part.24. A sampling tube comprising the assembly according to claim 2,characterized in that the sampling tube (20, 120) is filled with anadsorption material.
 25. The assembly according to claim 2,characterized in that the sampling tube (20, 120) has the shape of avial known per se.
 26. The assembly according to claim 2, characterizedin that the sampling tubes (20) used therein are provided with an inflowopening (26) and an outflow opening (25) which are situated on the sameend (20 a) of the sampling tube (20), while in a wall of the housing(29) of the chamber (K) of the adapter (19(both a supply (52) and adischarge (35) are provided which, in a condition of the sampling tube(20) when placed in the chamber (K), conntect to, respectively, theinflow opening (26) and the outflow opening (25) of the sampling tube(20).